Process for preparing detergent bars



PROCESS FOR PREPARING DETERGENTBARS Irving Rudolf Sehmolka, Long Island City, N.Y., assignor to Colgate-Pahnolive Company, Jersey City, N.J., a corporation or Delaware No Drawing. FiledSept. 28, 1955, Ser. No. 537,269

4 Claims. (Cl. 252-161) The present-inventionrelates to a processfforthepreparation of detergent bars. Moreppar'tieularly, it relates to a process .for preparing water soluble fatty acid monoglyceride sulfate detergent salts in the form of bars or cakes which lather freely and quickly in useand which are relatively non-sloughing on the washstand.

It has previously been proposed to prepare toilet bars from plasticized fatty acid monoglyceride sulfate detergent'salts. B-arsprepared'from these salts, incommon with bars prepared from other sulfated detergents, experience considerable sloughing and tend to become undesirably soft and smeary when left in contact with Water as in a wet soap dish. Apparently this =iscaused by the relatively high solubility of these detergents, and efforts to combat this problem have included the replacement, in the bars, of part of the detergent by various materials, both water soluble and insoluble. However, none of the prior procedures hasbeen completely satisfactory.

A process has now been found by which it ispossible to prepare relatively non-sloughing toilet :bars from water soluble fatty acid monoglyceridefsulfate detergent salts.

In the preparation of fatty acid'monoglyceride sulfate salt for use in toilet bars, the detergent is normally prepared by reacting fatty material, .glycerine and asulfating agent. Inevitably the neutralized sulfated product contains'unreacted free fatty acid. .It also normally contains some fatty acidmonoanddiglycerides. After neutralization of the sulfation product and unconsumed sulfating agent, alcohol extraction is employed toseparate the detergent active ingredient fromthe by-productinorganic salt formed on neutralization of the unconsumed sulfating agent. Being alcohol'soluble, the-fatt'y acids and partial glycerides remain with the alcohol soluble sulfated detergent salt, often forming a total of '10 to by weight of the mixture.

It-has now been found thatsloughin'g of 'ba'rsprepared from water soluble fatty acid mono'glyc'eride sulfate detergent salts can be markedly reduced by-removi'ngfrom the detergent, before it is shape'dinto'bar form, thelfatty acids normally associated therewith. This is indeed surprising, as the removal of the water insoluble'fatty acid. constituent serves to concentrate the rapidly-water soluble detergent material. The mechanism by which the'punified detergent becomes more slough-resistant at the same time that its total content of water soluble material is increased, is not clear.

'In accordance with the present invention, a process for the preparation of slough-resistant detergent bars comprises preparing a water soluble fatty acid monoglyceride sulfate detergent salt from fatty material, said detergent salt containing free fatty acid, removing said free fatty acid, plasticizing the resulting detergent'salt, "andshapingsaidplasticized detergent salt into bar form.

The water solublefatty acid monoglyceride sulfate .detergent salts and their'preparation by sulfation and neutralization'are well known -to the art. In'ge'neral they are prepared by reacting a fatty material (such as. a fa-t), glycerine, and asulfating agent (such as oleum). These materials are normally reactedin the approximatemolar ratios of 1:2:3 respectively. The sulfation product is neutralized with a base to prepare a suitable water soluble salt thereof, e.g. alkali metals such as sodium, potassium, and lithium, magnesium, .and ammonium and mono-, diand triethanolamiue salts, and then is alcohol extracted to prepare a product relatively free of inorganic salt, i.e. containingless than 10% thereof. Examples of fatty materials suitable for use in the present invention are the higher fatty triglycerides of fatty acids containing about 12 to 18 carbon atoms, e.g. oleic acid, myristie acid, palmitic acid, and mixtures thereof such as may be derived from coconut oiland tallow. Of course other fatty materials may serve as the source of these acids including partial glycerides and the fatty acids per so.

In the course of carrying out the present invention, it is necessary to remove from the neutralized detergent salt substantially all of the free fatty acid contained therein (e.g. to reduce the content of free fatty acid to less than'about 1% by weight of the detergent salt). This may easily be carried out by' extracting the detergent salt with a selective solvent in which free fatty acid is soluble and the detergent salt is insoluble. Suitable selective solvents include diethyl ether, diisopropyl ether, petroleum ethers (which 'are not ethers per se but rather are low boiling'hydrocarbons), and the like. When using a selective solvent such as diethyl ether for instance, the

extraction is carried out using dry or aqueous crude neutralized sulfation product under conditions of acidity such that the free fatty acid exists as the ether soluble acid form v(as-contrastedto the soap 'form'whi'ch is ether insoluble), while the fatty acid monoglyceride sulfate salt exists in the ether insoluble salt form. A suitable state of acidity is'onewherein a dilute, e.g. 1%, aqueous solution of the crude detergent salt has a pH "fromabout 5.0 to about 7.0.

It has been found that when employing ethyl ether extraction as a removal means, that there are normally removed, in addition to the free fatty acid, unsulfated -mono and diglycerides present in the crude detergent salt. Typically, crude detergent contains from about 6% to about 15% ether solubles, which consists of about equalparts by weight of free fatty acids and unsulfate'd esters which are principally fatty acid monoglycenides. While removal of the fatty acid monoglyceridesis not of particular consequence as regards the sloughing characteristics of the final bars, it has considerable merit in that removal of these monoglycerides, which'act as plasticizers for the detergent and which occur in different amounts in different batches of the detergent, vastly improves the uniformity of thephysical characteristics o f'the detergent which is .to be fabricated into bar form byniilling and plodding. [known non-uniform material, constant variations inprocessing conditions and juggling of the amount of added plasticizer are required. Use of uniformly ether extracted material overcomes these vagaries. Typically, diethyl ether extracted fatty acid monoglyceride sulfate detergent salts as contemplated by the presentprocess usually contain less than about 2% and preferably less than about 1% total diethyl ether solubles. The variations -in-the physical properties thereof are negligible and thesloughing of bars prepared therefrom is relatively slight.

Ether extracted detergent possesses another inherent desirable feature. It is relatively non-tacky and thus causes much less difliculty, as compared to unextracted material, withrespect to sticking to processing 'andhandling equipment. Plasticization of fatty acid This is important as, with the previously monoglyceride sulfate detergent salts is known to be essential to their preparalong-chain polyhydric alcohol monoand distearates and u particularly the ether-alcohol fatty acid esters, i.e. dl-

ethylene glycol monostearates are especially useful. These compounds also function as emulsifying agents, thus promoting the formation of a synthetic detergent bar having a smooth, uniform texture throughout. Other organic plasticizing agents which may be used are the normally solid polyethylene glycols, glycerol monoesters of coconut fatty acid, ethylene glycol distearate, and the diethylene glycol monoand diesters of palmitic, myristic, oleic, laun'c and coconut oil acids; propylene glycol monoand diesters of stean'c, oleic, lauric, myristic, palmitic, coconut oil fatty acids, etc., as well as suitable glyceryl and ethylene glycol monoesters of such fatty acids, and the like, which esters are normally solid, or oily liquids, and which dissolve in water but at a slow rate. Mixtures of the various organic compounds may, of course, be employed.

Suitable amounts of other substances, such as fillers, builders, coloring material, perfume, and the like also may be incorporated to produce a finished product having the physical characteristics desired. The temperature to which the detergent mass is subjected during milling and plodding will depend largely upon the particular composition involved, but normal plodding temperatures are between about 115 F. and about 145 F.

The following examples are given to additionally illustrate the nature of the invention, and it will be understood that the invention is not limited thereto. (All parts are by weight unless otherwise specified.)

Example I A mixture of equal parts of hydrogenated coconut oil and hydrogenated tallow are reacted with glycerine and oleum in the molar ratio of about 1:2:3 respectively. The product is neutralized to a pH of about 6.0 with sodium hydroxide, is then extracted with isopropyl alcohol and dried. The inorganic-salt-free extracted product contains a total of 13.32% by weight of material soluble in diethyl ether, this material consisting of about equal weights of free fatty acid and partial fatty glycerides. This crude product is solvent extracted with diethyl ether and the total diethyl ether content is diminished to 1.93%. This purified product is then compounded as follows:

Percent Ether extracted detergent 86.5 Zinc stearate 7.5 Diethylene glycol monostearate 4.0 Titanium dioxide 1.0 Perfume 1.0

These materials are dry mixed, and are then milled, plodded and pressed into final bar form.

The resulting bars are tested for sloughing by placing a weighed bar in a standard size soap dish (measuring about 4% inches long by 3% inches wide by 1 inch deep) and adding 35 ml. of distilled water to the dish. The dish containing the bar and the water is then stored for 24 hours at 70 F. and 55% relative humidity, after which time any soft slough is scraped from the surfaces of the bar and placed in the dish. The bar is then discarded and contents of the soap dish are dried to constant moisture at 194 F. The weight loss of the' bar represents the percentage of the bar appearing as dry residue. The test is repeated twice, using three bars and dishes for each run, and averaging the resultsv obtained from the total of six bars. I

When subjected to this test, the bars of this example exhibit an average weight loss of 4.8% as compared to 8.8% for bars prepared similarly except that the initial unextracted detergent is employed.

Example II A second batch of detergent is prepared similarly to that of Example I. It contains 12.29% total diethyl ether solubles, which on extraction with diethyl ether are reduced to 0.67%. On carrying out sloughing tests similar to those set forth in Example I, the bars of this exhibit an average weight loss of 5.5%, whereas control bars prepared according to the same formula by employing the crude detergent exhibit a weight loss of 9.2%.

Powdered samples of both the ether extracted and the crude detergent of this example are tested for tackiness by a compression tackiness test which involves determining the minimum weight required to break a briquette of the powder when the weight is allowed to rest on top of the briquette. The diethyl ether extracted detergent is found to be considerably less tacky than the unextracted material, i.e. it collapses under less than onehalf the load necessary to fracture the briquette of crude material.

Although the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that. varia tions and modifications of this invention can be made and that equivalents can be substituted therefor without departing from the principles and true spirit of the invention.

What is claimed is:

l. A process for the preparation of slough-resistant detergent bars comprising preparing a water soluble fatty acid monoglyceride sulfate detergent salt from fatty material, said detergent salt containing more than about 1% free fatty acid and less than about 10% of inorganic salt, removing said free fatty acid in excess of 1% so as to produce a fatty acid-monoglyceride sulfate detergent salt containing less than about 1% of said free fatty acid, plasticizing the resulting detergent salt, and shaping said plasticized detergent salt into bar form.

2. A process for the preparation of slough-resistant detergent bars comprising preparing a water soluble fatty acid monoglyceride sulfate detergent salt from fatty material, said detergent salt containing more than about 1% free fatty acid and less than 10% inorganic salt, selectively extracting said free fatty acid in excess of 1% using di-ethyl ether as a selective solvent so as to produce a fatty acid monoglyceride sulfate detergent salt containing less than 1% of free fatty acid, plasticizing the resulting detergent salt, and shaping said plasticized detergent salt into bar form.

3. A process for the preparation of slough-resistant detergent bars comprising preparing a water soluble fatty acid monoglyceride sulfate detergent salt from fatty material, said detergent salt containing more than about 1% of free fatty acid and less than 10% inorganic salt, adjusting the acidity of said free fatty acid-containing detergent salt to a state wherein a dilute aqueous solution thereof has a pH from about 5 to 7, selectively extracting said free fatty acid in excess of 1% using di-ethyl ether as a selective solvent so as to produce a fatty acid monoglyceride sulfate detergent salt containing less than about 1% of said free fatty acid, plasticizing the resulting detergent salt, and shaping said plasticized detergent salt into bar form.

4. A process for the preparation of slough-resistant detergent bars comprising preparing a water soluble fatty acid monoglyceride sulfate detergent salt from fatty material, said detergent salt containing more than about 1% free fatty acid and less than about 10% of inorganic salt, selectively extracting said free fatty acid in excess of 1% so as to produce a fatty acid monoglyceride sulfate detergent salt containing less than about 1% of said free fatty 2,407,647 Badman Sept. 17, 1946 acid, plasticizing the resulting detergent salt, and shaping 2,462,758 Malkemus Feb. 22, 1949 said plasticized detergent salt into bar form. 2,678,921 Turck May 18, 1954 2,687,420 Brady Aug. 24, 1954 References Cited in the file of this patent 5 2,868,812 Gray J an. 13, 1959 UNITED STATES PATENTS FOREIGN PATENTS 116-20636 Harris 25, 1938 477,521 Great Britain Dec. 28, 1937 

1. A PROCESS FOR THE PREPARATION OF SLOUGH-RESISTANT DETERGENT BARS COMPRISING PREPARING A WATER SOLUBLE FATTY ACID MONOGLYCERIDE SULFATE DETERGENT SALT FROM FATTY MATERIAL, SAID DETERGENT SALT CONTAINING MORE THAN ABOUT 1% FREE FATTY ACID AND LESS THAN ABOUT 10% OF INORGANIC SALT, REMOVING SAID FREE FATTY ACID IN EXCESS OF 1% SO AS TO PRODUCE A FATTY ACID MONOGLYCERIDE SULFATE DETERGENT SALT CONTAINING LESS THAN ABOUT 1% OF SAID FREE FATTY ACID, PLASTICIZING THE RESULTING DETERGENT SALT, AND SHAPING SAID PLASTICIZED DETERGENT SALT INTO BAR FORM 